According to the United States Census Bureau, the city has a total area of 3.7 square miles (9.6 km2), all of it land.

Alluvial soils such as Pardee cobbly loam is found throughout the Jackson area.

Therefore, areas along watercourses are considered likely locations for prehistoric cultural resources.

Surrounding areas were used for hunting and seed, acorn, and grass gathering.

Settlement of the region by American pioneers was stimulated by the discovery of gold in the Sierra foothills around 1848.

The camp became an important supply and transportation center for the neighboring towns, and by 1850, its population had reached an estimated 1,500.

Jackson grew first as a watering hole for cattle, then as one of the earliest and most durable of the mother lode's hard rock mining areas.

One of the town's most prominent historical landmarks, the Kennedy Mine, began operation in 1860; at the time of its closure during World War II in 1942, it was the deepest gold mine in North America, at 1802 m (5912 ft).

On August 27, 1922, 47 miners became trapped when a fire broke out in the Argonaut mine.

In October 1942, the US government passed the War Production Board Limitation Order, which signaled the demise of gold mining in California.

The 2,309 housing units had an average density of 619.0 per square mile (239.0/km2),of which 2,065 were occupied, 1,122 (54.3%) by the owners and 943 (45.7%) by renters.

The homeowner vacancy rate was 4.9%; the rental vacancy rate was 5.8%; 2,305 people (49.6% of the population) lived in owner-occupied housing units and 2,118 people (45.5%) lived in rental housing units.